Field of the Invention
The invention relates to novel insulin analogues with basal time/action profile, their preparation and use.
Description of the Art
The incidence of diabetes has increased in recent years to an almost epidemic extent. The disorder may result in a serious shortening of life expectancy. People with diabetes must frequently supply their body with insulin from outside. It is sensible to optimize the treatment with insulin. Different insulins with specific pharmacological properties are now available. In practice, the different insulins are differentiated according to their duration of action into short-acting insulins, fast-acting insulins, long-acting insulins and mixed insulins. Designations used synonymously for long-acting insulins are slow insulins, depot insulin or else basal insulin. The active ingredients in many of these insulin products are so-called insulin analogues which have been derived from human insulin by substitution, deletion and/or addition of one or more amino acids. The terms “insulin analogues” and “insulins” are used synonymously herein.
The policy of intensified insulin therapy attempts to diminish the health risk by aiming at a stable control of the blood glucose level by early administration of basal insulins. One example of a current basal insulin is the medicament Lantus® (active ingredient: insulin glargine=Gly (A21), Arg (B31), Arg (B32) human insulin). The general aim of developing novel, improved basal insulins is to minimize the number of hypoglycemic events. An ideal basal insulin in this connection is one acting reliably for at least 24 hours in each patient. The insulin effect ideally has a delayed onset and a time/action profile which is as shallow as possible, so that the risk of brief hypoglycemia is distinctly minimized and administration is even possible without previous intake of foodstuffs. There is a good supply of basal insulin when the insulin effect persists at the same level for as long as possible, i.e. the body is supplied with a constant amount of insulin. The risk of hypoglycemic events is thus low and a patient- and a day-specific variability is minimized. The pharmacokinetic profile of an ideal basal insulin should thus be characterized by a delayed onset of action and by a delayed, i.e. long-lasting and uniform, action.
However—despite the therapeutic advantages already achieved—none of the slow insulins described to date shows the pharmacokinetic properties of an ideal basal insulin. Desirable insulins have such a shallow and long-lasting time/action profile that the risk of hypoglycemic events and of the day-dependent variations in the patient is further minimized and the duration of action is further delayed, so that it is no longer necessary in some circumstances to administer insulin daily. This would make simplified treatment of diabetics possible, especially of elderly diabetics and those in need of care, who are no longer able to inject insulin themselves, and would thus also be of great economic benefit. Such basal insulins would additionally be beneficial in the early phase of type 2 diabetes. Clinicians report that the injection phobia present in many people deters them from starting insulin therapy in good time. As a consequence, the control of blood glucose is poor, leading to the late sequelae of diabetes. A basal insulin which reduces the number of insulin doses given by injection might have the effect of making insulin therapy more acceptable to patients.
Kohn et al. (Peptides 28 (2007) 935-948) describe how it is possible to optimize the pharmacodynamics of insulin by preparing insulin analogues whose isoelectric point (pI) is shifted, by addition of lysine or arginine at the B chain end or at the N terminus of the A and B chain, in the direction of the alkaline range compared with the isoelectric point of human insulin (pI=5.6), so that the solubility under physiological conditions is reduced and a prolonged time/action profile results. Compound 18 from Kohn et al. (Arg (A0), Gly (A21), Arg (B31), Arg (B32) human insulin (experimentally determined pI=7.3; calculated pI=7.58) is described in this connection as the best compound in the context of the idea. Kohn et al. therefore regard the main aim in designing novel insulin analogues as being the addition of positively charged amino acids to the amino acid sequence of human insulin for the purpose of increasing the isoelectric point from pI=5.6 into the neutral range.
This aim in the design of novel insulin analogues is the opposite of substitution of neutral amino acids in human insulin by acidic amino acids and/or addition of acidic amino acids, because such a substitution and/or additions at least partly abolishes the effect of introducing positively charged amino acids. However, it has now surprisingly been found that the described desirable basal time/action profile is obtained with insulin analogues which are characterized by the features that                the B chain end consists of an amidated basic amino acid residue such as lysine or argininamide, and        the N-terminal amino acid residue of the insulin A chain is a lysine or arginine residue, and        the A8 amino acid position is occupied by a histidine residue, and        the A21 amino acid position is occupied by a glycine residue, i.e. in the amidated basic amino acid residue at the B chain end the carboxyl group of the terminal amino acid is present in its amidated form, and        there have been two substitutions of neutral amino acids by acidic amino acids, two additions of negatively charged amino acid residues or one such substitution and one such addition respectively in the A5, A15, A18, B-1, B0, B1, B2, B3 and B4 positions.        
Whereas the first three features mentioned tend, through introduction of positive charges or elimination of negative charges, to contribute to increasing the pI of a corresponding insulin analogue, the last-mentioned substitutions and/or additions of negatively charged amino acid residues have the opposite effect and contribute to reducing the pI. Surprisingly, precisely the insulin analogues described have the desired advantageous time/action profiles. The pI values of these compounds are lower than that of compound 18 from Kohn et al. (Arg (A0), Gly (A21), Arg (B31), Arg (B32) human insulin), but nevertheless moreover show a delayed onset of action and a longer duration of action, i.e. an extremely shallow and long-lasting, uniform action profile. The risk of hypoglycemic events is thus distinctly minimized. The delay is so marked that it is surprisingly possible to detect the effect even in model experiments on rats, although the delayed action of insulin glargine cannot by contrast be unambiguously observed in rats. FIG. 1 shows the hypoglycemic effect of the compound YKL205 of the invention compared with that of insulin glargine. Similar results are obtained in dogs (see FIG. 2). Thus, novel basal insulins which need to be administered distinctly less frequently have been provided. Besides these pharmacokinetic advantages described, the analogues of the invention show distinctly better properties compared with insulin glargine in pharmacological respects such as, for example, receptor specificity and in vitro mitogenicity. The claimed insulins also show advantages in physicochemical respects.